Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
  • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
  • B02C17/00—Disintegrating by tumbling mills, i.e. mills having a container charged with the material to be disintegrated with or without special disintegrating members such as pebbles or balls
  • B02C17/18—Details
  • B02C17/22—Lining for containers
  • B02C17/225—Lining for containers using rubber or elastomeric material
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S241/00—Solid material comminution or disintegration
  • Y10S241/30—Rubber elements in mills
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
  • Y10T428/269—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension including synthetic resin or polymer layer or component
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31551—Of polyamidoester [polyurethane, polyisocyanate, polycarbamate, etc.]
  • Y10T428/31569—Next to natural rubber
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31551—Of polyamidoester [polyurethane, polyisocyanate, polycarbamate, etc.]
  • Y10T428/31573—Next to addition polymer of ethylenically unsaturated monomer
  • Y10T428/31587—Hydrocarbon polymer [polyethylene, polybutadiene, etc.]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31826—Of natural rubber
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31826—Of natural rubber
  • Y10T428/3183—Next to second layer of natural rubber

Definitions

• Wear-resistant rubber products are used to a large extent in the mining industry, especially in chutes and, primarily, in mills for grinding ore.
• a wear-resistant lining consisting of shell plates and so-called lifters which extend into the drum mill and stir the charge within the rotating mill drum and which therefore are subjected to an exceptionally high wear.
• the lifters must be replaced on more than one occasion during the life of the mill lining or, strictly speaking, the shell plates. Normally, the worn lifters are replaced by new ones, and the worn lifters frequently are scrapped.
• the worn-out lifters usually still carry large quantities of rubber since the lifters must be replaced before the grinding capacity which is. dependent upon the lifter geometry, has decreased to an unacceptably low level.
• OMPI pre-vulcanized treads to used carcasses requires care ⁇ ful shaping (abrading) of the rubber surface of the used detail to make it conform to the shape of the new vulcanized rubber detail which is vulcanized to the old rubber detail.
• a wear-resistant rubber product which is to be used as, for example, a lifter in grinding mills thus comprises at least two pre ⁇ fabricated parts interconnected by means of a binder layer of in situ cast and vulcanized polyurethane having a thickness of at least 2 mm (preferably at least 5 mm) .
• the wear-resistant rubber product is made by placing the prefabricated vulcanized rubber parts at a distance of at least 2 mm (preferably at least 5 mm) from one another and filling the gap with a reacting urethane rubber composition with excess isocyanate so that the pre- fabricated parts on either side of the gap are contacted substantially simultaneously by said urethane rubber composition.
• the wear-resistant rubber product may be either a new product or a recapped product in which parts of a used corresponding wear-resistant rubber product have been connected with at least one prefabricated vulcanized wear-resistant rubber body by means of the in situ cast and vulcanized urethane rubber layer, said prefabricated and vulcanized rubber body having a profile adapted to that of the future product. Since the conditions of pre ⁇ fabricating this rubber body are far more readily controlled, a high-quality wear-resistant rubber body can be obtained. Hot recapping by vulcanizing an uncured rubber compound to an old and worn product in a vulcanizing mould always necessitates a compromise between on one hand
• the product may be formed of at least two parts, one of which comprises a holder and the other consists of a prefabricated cured wear- resistant rubber body of a profile suitable for the future lifter.
• the part comprising the holder consists of a worn lifter, the surface of which is prepared by cleaning and, if necessary, also by buffing.
• Such a worn lifter may comprise a metal component with attachment means and a rubber part vulcanized thereto.
• the prefabricated part or parts used for the manufacture may consist of extruded or moulded cured wear-resistant rubber bodies which, however, must be relieved of theirvulcanization skin by some simple surface treatment, such as sawing or cutting. On the other hand, it is not always necessaryto buff the rubber bodies, and no primer need be applied.
• the cured wear-resistant rubber bodies and the worn lifter can be processed with equipment less expensive than that used in, for example, the complete or partial recapping of tires.
• the prefabricated parts preferably are placed on a casting substrate in such a manner that the minimum spacing between their surfaces to be inter- connected will be 2 mm, preferably 5 mm. In this manner, a gap is formed, the ends of which are closed to form an upwardly open mould cavity into which the reacting urethane rubber composition is then introduced, preferably injected.
• the minimum spacing of 2 mm, preferably 5 mm, is conditioned by the requirement that it shall be possible for the reacting urethane rubber composition safely to enter and fill out the gap between the bodies and to contact the bodies substantially simultaneously.
• the rubber parts to be joined together may have room temperature when contacted by the hot urethane rubber composition.
• the urethane rubber composition preferably is introduced at a temperature of 75-150°C.
• the upper limit is conditioned by the fact that the time or pot life during which the compounded urethan ⁇ rubber composition can be used will be too short if the casting temperature exceeds 150°C.
• FIG. 1 and 2 diagramatically illustrate two possible procedures in the manufacture of a wear- resistant rubber product according to the present in ⁇ vention.
• Fig. 1 shows a casting mould 10 in which a worn lifter 11 and a prefabricated wear-resistant rubber body 12 have been placed lying on their sides, such that a gap 13 having a minimum width of at least 2 mm is formed therebetween.
• the gap is being filled with a reacting urethane rubber composition from an injection nozzle 14 which is moved along the gap and in which the components of the urethane rubber composition are mixed immediately before the composition leaves the nozzle.
• the injection nozzle preferably is inserted into the gap, thereby to cause the liquid urethane rubber composition to rise and gradually to expel the air within the gap and to contact both rubber bodies substantially at the same time.
• Fig. 2 shows the manufacture of a new wear-resistant rubber body according to the present invention, the components of which have not previously been used. In this case, a sectional metal element 15 has been placed
• OMPI in the center of the bottom of a casting mould l ⁇ .
• Two pre ⁇ fabricated, cured wear-resistant rubber bodies 17, 18 have been rigged up in the casting mould by means of small spacer members (not shown) provided at the ends thereof and, if necessary, also at one or more points along the length of the rubber bodies so that an inverted Y-shaped gap 19 is formed between the bodies 17, 18 and the sectional metal element 15.
• a needle-shaped nozzle 20 is used for filling the gap 19 with the liquid reacting urethane rubber composition.
• Example 1 In this Example, use was made of a worn lifter, the rubber part of which was formed of wear-resistant rubber based upon styrene-butadiene rubber and having a hardness of 60 Shore A.
• the worn lifter was cleaned and slightly buffed on its surface.
• the lifter had a length of 1 m and a width of 2 dm.
• the lifter and a prefabricated sectional rubber element of the same rubber type were placed overnight in a warming cupboard having a temperature of 110 C.
• the bonding surface of the pre ⁇ fabricated sectional rubber element was conditioned by removal of a surface layer.
• the lifter was laid on its side on a plastic fabric (polytetrafluoroethylene) on a casting table.
• the sectional rubber element was placed alongside of the lifter, such that the minimum distance between this surface and the curved worn surface of the lifter was at least 2 mm.
• the ends of the resulting gap between the lifter and the sectional rubber element were sealed by pressing mould side walls against the lifter and the rubber sectional element.
• a reacting urethane rubber composition was then injected into the gap by means of the nozzle of a mixer/injector that was inserted in the gap in order to fill said gap while expelling the air.-
• the two rubber surfaces were contacted with the reacting urethane rubber composition substantially simultaneously, which is of essential importance to the reliability of the bond. r ..-PI ' .IPO
• the urethane rubber composition the following two-component system was used:
• polyester prepolymer having about 6.5% of available iso- cyanate groups (MDI, i.e. methylene-bisphenylene- diisocyanate)
• This recipe implies a curing agent content of 95%, based upon the available isocyanate groups.
• the two rubber details had a temperature of 90-100 C, and the urethane rubber composition injected into the gap had a mixing temperature of 110 C. After the gap had been filled, the"components were left on the casting table until the urethane rubber composition had solidified and obtained sufficient strength to allow handling of the lifter and the sectional rubber element attached thereto. The product was then stored at room temperature for 72 hours.
• transverse test pieces having a thickness of 25 mm were taken by sectioning.
• the pieces or samples were then subjected to adhesion tests, so-called peeling tests.
• the peel strength was found to be 26.5 kN/m, the rupture occuring in the styrene butadiene rubber material, not in the joint between the urethane rubber and styrene butadiene rubber materials.
• Example 1 was repeated, and both rubber components were buffed.
• Example 3 Example 1 was repeated, except that no drying and preheating in a warming cupboard occured, which means that both rubber components had room temperature.
• the peel strength was 14.6 kN/m, and the rupture occured in the joint between the rubber materials. This test shows that an acceptable strength is obtainable also with cold rubber, but that higher strength values will be obtained if the rubber components are preheated and dried.
• Example 4 worn lifters and prefabricated sectional rubber elements of the same material and having the same dimensions as the lifter and the sectional rubber • element of Example 1 were used.
• the worn lifters were cleaned and slightly buffed, and a surface layer of the sectional rubber elements was removed to expose fresh rubber.
• the lifters and the sectional rubber ele- ments were preheated, overnight in a warming cupboard having a temperature of 100 C.
• Each lifter was then placed in a shallow casting mould which stood on a casting table and had such dimensions that the lifter in upright position, i.e. with the metallic holder facing downwardly, fitted closely in the casting mould, the edges of which protruded beyond the rubber part of the worn lifter.
• Example 2 In a first test, the lifter was covered with the urethane rubber composition stated in Example 1, and the sectional rubber element was gradually pressed down into the reacting urethane rubber composition within half a minute. In a second test, the sectional rubber element was pressed down into the reacting urethane rubber composition 2 minutes after the lifter placed in the casting mould had been covered with the urethane rubber composition. 72 hours after casting, an adhesion test was made, and the peel strength was found to be 18.6 kN/m in the first test and but 6.2 kN/m in the second test. This Example shows that it is of essential importance that the rubber bodies to be joined together will contact the urethane rubber composition substantially simultaneously.
• Example 2 was repeated with a polyether prepolymer and a different curing agent composition.
• the rubber material in the lifter and in the sectional rubber element was the same as in Example 1.
• the prepolymer and the curing agent composition were as follows: Prepolymer
• the rupture occured in the s yrene butadiene rubber material, not in the joint between the rubber materials.

Landscapes

• Engineering & Computer Science (AREA)
• Food Science & Technology (AREA)
• Casting Or Compression Moulding Of Plastics Or The Like (AREA)
• Manufacture Of Macromolecular Shaped Articles (AREA)
• Graft Or Block Polymers (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

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ID=20339254

Family Applications (1)

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Cited By (5)

Families Citing this family (11)

Citations (3)

Family Cites Families (6)

• 1979
  • 1979-11-06 SE SE7909159A patent/SE421508B/sv not_active IP Right Cessation
• 1980
  • 1980-10-30 BR BR8008887A patent/BR8008887A/pt unknown
  • 1980-10-30 JP JP50246780A patent/JPS6148984B2/ja not_active Expired
  • 1980-10-30 DE DE8080902072T patent/DE3066865D1/de not_active Expired
  • 1980-10-30 US US06/261,226 patent/US4446192A/en not_active Expired - Lifetime
  • 1980-10-30 EP EP19800902072 patent/EP0039695B1/de not_active Expired
  • 1980-10-30 WO PCT/SE1980/000266 patent/WO1981001253A1/en active IP Right Grant
  • 1980-11-05 ES ES496568A patent/ES8200264A1/es not_active Expired
  • 1980-11-06 ZA ZA00806859A patent/ZA806859B/xx unknown
• 1981
  • 1981-05-13 NO NO811622A patent/NO154158C/no unknown
  • 1981-05-20 FI FI811558A patent/FI67495C/fi not_active IP Right Cessation

Patent Citations (3)

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